For example, when attempted to export electronic appliances such as electric hot box to various countries, since the commercial supply voltage differs in each country, it is necessary to replace the transformer to obtain a direct-current voltage for control.
The replacement of transformer is actually very difficult in design work, and it is not enough to prepare transformers corresponding to the commercial supply voltage of 110 V in Taiwan, 220 V in China, 120 V in United States, and 230 to 240 V in Europe, but an appropriate current suited to each appliance is needed, which may require renewal of design. Trial production, procurement and replacement of transformer take much time and labor, which results in high cost of the electronic appliances.